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<p class="MsoNormal">Hi Doug,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for the info. I know that JPEG is lossy but our datasets are very large. That’s why we use JPEG, which is good enough for our needs and the file sizes are smaller.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It seems that GDAL doesn’t create new JPEG files without having pre-existing JPEG-s to modify. If I try to modify old JPEG, I get a message “Output dataset exists, but cannot be opened in update mode.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I also tried using “CreateCopy” but that produced syntax error. Used command on GDAL CMD:<o:p></o:p></p>
<p class="MsoNormal">“GDALDriver::CreateCopy ("new.jpg","old.jpg", FALSE, NULL, NULL, NULL)”<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Kalev<o:p></o:p></p>
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<p class="MsoNormal"><b><span lang="ET">From:</span></b><span lang="ET"> Doug Newcomb <doug_newcomb@fws.gov>
<br>
<b>Sent:</b> Thursday, June 21, 2018 5:24 PM<br>
<b>To:</b> Kalev Julge <kalev.julge@reach-u.com><br>
<b>Cc:</b> gdal dev <gdal-dev@lists.osgeo.org><br>
<b>Subject:</b> Re: [EXTERNAL] [gdal-dev] Convert VRT+JPEG with gdalwarp<o:p></o:p></span></p>
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<p class="MsoNormal">Kalev,<o:p></o:p></p>
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<p class="MsoNormal">Just set the output file format to -f JPEG format ( .jpg) or -f JP2OpenJPEG (.jp2)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The JPEG format will be lossey by default. Is that what you want?<o:p></o:p></p>
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<p class="MsoNormal">See:<o:p></o:p></p>
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<p class="MsoNormal"> <a href="https://medium.com/planet-stories/a-gentle-introduction-to-gdal-part-1-a3253eb96082">https://medium.com/planet-stories/a-gentle-introduction-to-gdal-part-1-a3253eb96082</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><a href="https://medium.com/planet-stories/a-gentle-introduction-to-gdal-part-2-map-projections-gdalwarp-e05173bd710a">https://medium.com/planet-stories/a-gentle-introduction-to-gdal-part-2-map-projections-gdalwarp-e05173bd710a</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Doug<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Jun 21, 2018 at 10:00 AM kalevj <<a href="mailto:kalev.julge@reach-u.com">kalev.julge@reach-u.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hello,<br>
<br>
I used gdalwarp to transform a VRT+JPEG pair from one EPSG projection to<br>
another. Everything worked well. This conversion changed the VRT file so<br>
that reprojection takes place when the images are loaded. However, I would<br>
need to reproject the JPEG so that there would not be a need to reproject<br>
every time the images are loaded. Is it possible somehow?<br>
<br>
I used the command:<br>
"gdalwarp -s_srs EPSG:2006 -t_srs EPSG:3857 -of VRT -r near old.vrt new.vrt"<br>
<br>
Thanks!<br>
<br>
Kalev<br>
<br>
<br>
<br>
--<br>
Sent from: <a href="http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html" target="_blank">
http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html</a><br>
_______________________________________________<br>
gdal-dev mailing list<br>
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<a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev" target="_blank">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a><o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">Doug Newcomb<o:p></o:p></p>
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<p class="MsoNormal">USFWS<o:p></o:p></p>
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<p class="MsoNormal">551F Pylon Dr<o:p></o:p></p>
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<p class="MsoNormal">Raleigh, NC<o:p></o:p></p>
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<p class="MsoNormal">919-856-4520 ext. 14 <a href="mailto:doug_newcomb@fws.gov" target="_blank">
doug_newcomb@fws.gov</a><o:p></o:p></p>
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<p class="MsoNormal">---------------------------------------------------------------------------------------------------------<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><i><span style="font-size:9.5pt;color:blue">NOTE: This email correspondence and any attachments to and from this sender is subject to the Freedom of Information Act (FOIA) and may be disclosed to third parties.</span></i></b><span style="font-size:9.5pt;font-family:"Cambria Math",serif;color:blue"></span><o:p></o:p></p>
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